Since commit cb84343fced1 ("media: lirc: do not call close() or open() on
unregistered devices") rc_open() will return -ENODEV if rcdev->registered
is false. Ensure this is set before we register the input device and the
lirc device, else we have a short window where the neither the lirc or
input device can be opened.

Fixes: cb84343fced1 ("media: lirc: do not call close() or open() on unregistered devices")